COMPUTING MILESTONES — IBM PC launch date On which date did IBM debut its first IBM Personal Computer (Model 5150), a landmark moment in PC history?

Introduction / Context:
The IBM PC 5150 standardized a hardware and software ecosystem that influenced decades of computing. Knowing the launch date helps anchor timelines for DOS, x86 processors, and the growth of compatible clones.

Given Data / Assumptions:

• The question asks for the official debut date.
• We focus on the public announcement/release, not internal project milestones.
• U.S. date format is used in the options.

Concept / Approach:
IBM announced and released the IBM PC Model 5150 on August 12, 1981. This event catalyzed the MS-DOS ecosystem, third-party expansion cards, and a vast compatible market.

Step-by-Step Solution:
Recall the historically cited release date for the IBM PC 5150.Identify “August 12, 1981” among the choices.Select it as the correct answer.

Verification / Alternative check:
Technology history references and IBM archives consistently list 12 August 1981 as the launch date.

Why Other Options Are Wrong:
January 21, 1979 / August 21, 1980 / January 12, 1982 / September 1, 1981 — dates that do not match the documented debut of the IBM PC 5150.

Common Pitfalls:
Confusing the IBM PC launch with later releases like the XT (1983) or AT (1984). Each had its own milestone date.

Final Answer:
August 12, 1981